autoconfinarse

To place oneself in self-lockdown or quarantine — a word that entered everyday Spanish sharply during the COVID-19 pandemic (mucha gente se autoconfinó antes de que fuera obligatorio) and is still used for any voluntary, health-driven isolation.

• Mucha gente se autoconfinó antes de que fuera obligatorio. — A lot of people put themselves in lockdown before it became mandatory.
• Se autoconfinó al notar los primeros síntomas de gripe. — He self-quarantined as soon as he noticed the first flu symptoms.
• La familia decidió autoconfinarse durante dos semanas por precaución. — The family decided to self-isolate for two weeks as a precaution.

Treating autoconfinarse and confinar as interchangeable — confinar (someone) is what an authority does to you; autoconfinarse is the voluntary, self-initiated version.

Often confused with confinar.